Jo

Recently I was lamenting that it's no longer the case that 99% of educated Europeans read and write Latin, making international academic communication way more difficult. But today I found out that, even within the academy, English might actually be more widespread today than Latin was then!

In terms of stuff you can read, you're better off now. It says here that seventy percent of incunabula are in Latin. According to this sample, that percentage is today exceeded by English-language articles in psychology, sociology, probably educational sciences, economics, human geography, political science, and communication and media studies. Possible exceptions include history, archaeology, linguistics (unsurprising), literature (unsurprising), and art. The only definite exception in this sample is law, where English is firmly in the minority. (Some rando claims that ninety-eight percent of science publications are in English, but that can't be right.) 

(Also, about 90% of EU legislation is in English, it's the international language of flight, and it's supposedly spoken by one in seven humans.)

In terms of people you can write to, you're probably better off back then if you only want to talk to academics; I'm assuming that basically every academic back then could read Latin, whereas today not all of them are literate in English. However, if you want to talk to non-academics, you're better off speaking English today than Latin in 1500. European literacy rates around 1500 were abysmal, such that a minority could read at all. And presumably even fewer people could speak Latin. Whereas today, 38% of the EU can have a conversation in English, and I'm assuming all of those people can read it too.

What I haven't found numbers on is the later Renaissance. Perhaps in Shakespearean times, or Georgian times, Latin was more widespread.